Patent Document 1 describes a projector that uses a phosphor as a light source.
The principle parts of the projector described in Patent Document 1 are made up by a light source device, a cooling fan, a display element, and projection-side optics.
The light source device includes a light-emitting device in which the fluorescent color is red, a light-emitting device in which the fluorescent color is green, a light-emitting device in which the fluorescent color is blue, and first and second dichroic mirrors that combine the fluorescent light of each color from these light-emitting devices.
Each light-emitting device includes a cylinder-shaped rotating body in which a phosphor layer is formed on the outer periphery, a drive source that rotates the rotating body, a collimator lens that converts the fluorescent luminous flux emitted from the phosphor layer to parallel luminous flux, an excitation light source, and a mirror that reflects excitation light from the excitation light source in the direction toward the phosphor layer. The excitation light that is reflected by the mirror is irradiated by way of the collimator lens onto the phosphor layer. The fluorescent light that is emitted from the phosphor layer is converted to parallel luminous flux by the collimator lens.
The blue fluorescent light that is emitted from the blue light-emitting device is entered to one surface of the first dichroic mirror and the green fluorescent light that is emitted from the green light-emitting device is entered to the other surface of the first dichroic mirror. The first dichroic mirror has the property of transmitting blue light but reflecting green light and thus combines the incident blue and green fluorescent light.
The fluorescent light (green and blue) that is combined in the first dichroic mirror is entered to one surface of the second dichroic mirror, and red fluorescent light that is emitted from the red light-emitting device is entered to the other surface of the second dichroic mirror. The second dichroic mirror has the property of transmitting blue and green light but reflecting red light and thus combines the incident blue, green, and red fluorescent light.
Each light-emitting device is arranged in a chamber that is supplied with an air current from a cooling fan. Each light-emitting device is cooled by supplying the air current from the cooling fan to each light-emitting device.
In the above-described projector, light from the light source device is irradiated to a display element, and the image formed in this display element is then projected onto a screen by projection-side optics.
In addition to the above-described projector, Patent Document 2 describes a projector that uses light-emitting diodes (LED) as a light source.
The projector described in Patent Document 2 has illumination optics that includes: a red LED array in which a plurality of red LEDs are arranged, a green LED array in which a plurality of green LEDs are arranged, a blue LED array in which a plurality of blue LEDs are arranged, and a cross dichroic prism that combines the luminous flux for each of the colors red, green, and blue from these LED arrays.
In the above-described projector, light from the illumination optics is irradiated into a digital micro-device (DMD) and the image formed by the DMD is projected onto a screen by projection lenses.